Optical disc and optical disc driving device

ABSTRACT

An optical disk having a plurality of substantially concentric tracks, each of which includes a plurality of segments each comprising a servo area ARs provided with servo pits for giving servo information to a disk drive and a data area ARd. Identification marks SGM, ADM, STM1, STM2 are recorded in the servo area ARs. The identification marks SGM, ADM, STM1, STM2 provide information for identifying the respective segments depending on the recording position in the servo area ARs.

This is a divisional of application Ser. No. 09/082,733, filed May 21,1998, which was a divisional of U.S. Pat. No. 08/632,428 filed Nov. 12,1996.

TECHNICAL FIELD

This invention relates to an optical disc of the sample servo system anda driving device therefor.

BACKGROUND ART

There has hitherto been known an optical disc system forrecording/reproducing various data by scanning a concentrically orspirally extending track on the disc by a laser beam, in which theoptical disc is driven at a constant linear velocity (CLV) or at aconstant angular velocity (CAV) for recording/reproducing the data.There has also been known an optical disc system of a continuous servosystem in which tracking control is performed using a continuouspre-groove formed along the track, or of a sample servo system in whichtracking control is performed using discrete servo areas formed on thetrack.

Among known types of the optical discs, there are a recordable RAM disc,such as a replay-only ROM disc, a write-once disc or a magneto-opticaldisc (MO disc) and a so-called partial ROM disc having both ROM and RAMareas.

An optical disc system, handling such optical disc, is configured forreading the parameter information for the medium recorded on a phaseencoded part (PEP) provided on an inner rim of the optical disc asprescribed in ISO MO 5.25 inch standards and for reading the controlinformation from the control track based upon the control informationfor carrying out the control operation responsive to the controlinformation.

With the continuous composite servo system (CCS system) standardized inISO, servo data is affected by data per se. That is, if data recordingdensity is increased, system clocks can be reproduced with increasingdifficulties, such that it becomes difficult to achieve high recordingdensity. Besides, since the groove and pits must be cut simultaneously,it is difficult to produce a ROM disc or a partial ROM disc.

In addition, with the conventional optical disc, a dedicated decodingcircuit has been required for reading out the parameter informationrecorded on the PEP. Since the PEP lacks in the address information, thepickup position cannot be identified. Since the PEP and the recordingarea for data per se are different in formats, the two areas need to bedemarcated from each other via a gap.

It is therefore an object of the present invention to provide an opticaldisc of a sample servo system of high capacity and high performance, anda driving system therefor.

It is another object of the present invention to provide an optical discin which the parameter information can be read without requiring adedicated decoding circuit and in which the pickup position can beidentified.

DISCLOSURE OF THE INVENTION

The present invention provides an optical disc having a plurality ofsubstantially concentrically extending tracks, each track including aplurality of segments having a servo area having servo pits giving theservo information to a disc drive and a data area. There is provided adiscrimination mark giving the information for identifying a segment bythe recording position in the servo area.

With the optical disc of the present invention, the segments include adata segment for recording user data and an address segment forspecifying an address of the data segment. The discrimination markdiscriminates the data segment from the address segment.

With the optical disc of the present invention, a sector is formed by aplurality of segments and a segment at a leading end of the sector isidentified by the discrimination mark.

With the optical disc of the present invention, a sector is formed by aplurality of segments and a segment at a leading end of the sector and adirectly previous segment are identified by the discrimination mark.

With the optical disc of the present invention, the segments include adata segment for recording user data and an address segment specifyingan address of the data segment, and a plurality of said segments make upa sector. The data segment and the address segment may be discriminatedfrom each other by the discrimination mark and the segment constitutingthe leading end of the sector and the directly previous segment may bediscriminated from each other by the discrimination mark.

With the optical disc of the present invention, a segment directlyprevious to the segment at the leading end of the sector is identifiedby said discrimination mark.

The present invention also provides an optical disc having a pluralityof substantially concentrically extending tracks, each track including aplurality of segments having a servo area having servo pits giving theservo information to a disc drive area, and a data area, in which thesegments are made up of address segments arranged at the same positionsin the radial direction of the tracks and having the address informationrecorded in said data area, and a data segment for recording user data,and in which the address information is recorded in the address segmentin the gray code representation using a region of five clocks for the2-bit information. The clocks are generated by a disc drive based uponthe servo pits.

The present invention also provides an optical disc having a pluralityof substantially concentrically extending tracks, each track including aplurality of segments having a servo area having servo pits giving theservo information to a disc drive, and a data area, in which pluralsegments are made up of address segments formed at the same position inthe radial direction of each track and having the address informationrecorded in each data area and a data segment for recording user data.The address information is recorded as bits in 4-bit gray coderepresentation in a 11-clock area of the clock signals in said addresssegment, upper two bits in the four bits corresponding to 5 clocks bythe gray code representation and the lower two bits corresponding to 5clocks in the gray code representation, and one clock therebetween. The1-clock area has a pit formed therein when the pit representing theupper two bits in the gray code representation and the pit representingthe lower two pits in the gray code representation are at the shortestdistance from the one-clock area and when one of the pits is at theshortest distance and the outer is at the longest distance from theone-clock area.

With the optical disc of the present invention, plural servo pits arerecorded in the servo area so as to have an area of two clock signalsand a distance of not less than 5 pits.

With the optical disc of the present invention, scrambled and NRZIconverted data is recorded in said data segment.

With the optical disc of the present invention, a pre-write area havingdata of a pre-set polarity recorded therein is provided at a leading endof a data area of the data segment.

With the optical disc of the present invention, a post-write area havingdata of a pre-set polarity recorded therein is provided at a trailingend of a data area of the data segment.

The present invention also provides an optical disc having a pluralityof substantially concentrically extending tracks, each track including aplurality of segments arranged in the same radial direction relative tothe track and having a servo area having servo pits giving the servoinformation to a disc drive, and a data area, in which the optical discis divided into plural zones each having a uniform number of sectors bysetting the relation of the number of servo clocks SCKseg per segmentand the number of data clocks DCKseg per segment, wherein M and N areintegers.

With the optical disc of the present invention, the number of servoclocks SCKseg per segment is set to SCKseg=9N.

With the optical disc of the present invention, the next zone is startedfrom the next segment even if there is a redundant area in the lastsegment of a zone and the start segments of the respective zones arearrayed at the same radial positions.

The present invention also provides an optical disc having a pluralityof substantially concentrically extending tracks, each track including aplurality of segments having a servo area having servo pits giving theservo information to a disc drive, and a data area, in which thesegments include address segments arranged in the same radial directionof the track and adapted for recording the address information in thegray code representation in the data area, and a data segment forrecording user data, and in which a media information area in which themedia information coded in the same gray code representation as theaddress information is recorded in a data area of a portion of theplural tracks.

With the optical disc of the present invention, the media informationarea is formed across plural consecutive tracks.

With the optical disc of the present invention, the media information ofthe same contents is recorded in data areas of the same angular positionof the consecutive plural tracks.

With the optical disc of the present invention, the media informationarea is provided in each of inner rim and outer rim regions.

With the optical disc of the present invention, the media information isrecorded in each data area of a portion of said tracks.

With the optical disc of the present invention, the address informationis recorded in said address segment as gray code using an areacorresponding to five clocks generated by a disc drive based on theservo pits for the information of two bits.

With the optical disc of the present invention, address information isrecorded as bits in 4-bit gray code representation in a 11-clock area ofsaid clock signals in said address segment, upper two bits in the fourbits corresponding to 5 clocks by gray code representation and the lowertwo bits corresponding to 5 clocks in gray code representation, and oneclock therebetween. The 1-clock area has a pit formed therein when thepit representing the upper two bits in gray code representation and thepit representing the lower two pits in the gray code representation areat the shortest distance from the one-clock area and when one of thepits is at the shortest distance and the outer is at the longestdistance from the one-clock area.

With the optical disc of the present invention, media informationindicates a once-write type or a replay-only type.

With the optical disc of the present invention, the media informationfor the same contents is recorded in plural data areas of said portionof the tracks.

The present invention also provides an optical disc having a pluralityof substantially concentrically extending tracks, each track including aplurality of segments having a servo area having servo pits giving theservo information to a disc drive, and a data area, in which thesegments are made up of address segments arranged at the same positionsin the radial direction of the tracks and having the address informationrecorded in the data area, and a data segment for recording user data,and in which a media information area having recorded therein the mediainformation in the gray code representation is formed in a plurality oftracks in the vicinity of the inner rim and in a plurality of tracks inthe vicinity of the outer rim.

The present invention also provides an optical disc driving device fordriving an optical disc in which the optical disc has formed thereon aplurality of substantially concentrically extending tracks, each trackhaving a plurality of segments each having a servo area having servopits giving the servo information to the disc drive and a data area, adiscrimination mark being provided in the servo area for representingthe information for discriminating the segment by the recording positionin the servo area. The optical disc driving device includes reproducingmeans for reproducing the information recorded on the optical disc,detection means for detecting the position of the discrimination mark byplayback signals reproduced by the reproducing means from thediscrimination mark by a differential detection method, anddiscrimination means for discriminating the segment based upon theresults of detection by the detection means.

The present invention also provides an optical disc driving device fordriving an optical disc in which the optical disc has formed thereon aplurality of substantially concentrically extending tracks, each trackhaving a plurality of segments each having a servo area having servopits giving the servo information to the disc drive and a data area, anda pre-write area unified to a polarity at the distal end of the dataarea. The optical disc driving device includes recording/reproducingmeans for reproducing data from the optical disc and for recording dataon the optical disc, driving power producing means for producing alow-level playback driving power or a high-level recording driving powerto the recording/reproducing means, data supplying means for supplyingrecording data to the recording/reproducing means, and control means forcontrolling the driving power producing means so that the driving poweris switched from the playback driving power to the recording drivingpower during recording at a timing the optical pickup of therecording/reproducing means is moved from the servo area to thepre-write area of the data area. The control means controls said datasupply means for supplying data of the same polarity as the one polarityto the optical pickup. The control means controls the data supplyingmeans for supplying desired data to the optical pickup at a timing thepickup traverses the pre-write area.

With the optical disc of the present invention, clamping means forclamping the data reproduced by the recording/reproducing means at atiming of the pre-write area during reproduction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a segment structure of an optical disc according tothe present invention.

FIGS. 2A to 2E illustrate a format of mainly a servo area when theoptical disc is a MO disc. FIG. 2A shows clocks in a servo area and aadata area, FIG. 2B shows a servo area having a segment mark SDG, FIG. 2Cshows a servo area having an address mark ADM, FIG. 2D shows a servoarea having a first sector mark STM1 and FIG. 2E shows a servo areahaving a second sector mark STM2.

FIG. 3 shows a detection system for detecting a first pit in the servoarea in the above optical disc.

FIG. 4 shows a format of an address segment in the above optical disc.

FIG. 5 shows a portion of an access code recorded in the address segmentshown in FIG. 4.

FIG. 6 shows a format of a data segment in the optical disc.

FIG. 7 shows a format of mainly a servo area in a ROM disc.

FIG. 8 shows the constitution of an I-frame and an I-data sector of theoptical disc.

FIG. 9 shows the data format of a data sector of the optical disc.

FIG. 10 shows playback signals which is based on a reference pattern ofthe data sector of the optical disc.

FIG. 11 shows a setting parameter of area division in the optical disc.

FIG. 12 shows the state of area division in the optical disc.

FIG. 13 shows a data format in the optical disc.

FIG. 14 shows the arraying state of a GCP segment in the optical disc.

FIG. 15 shows the construction of the GCP segment.

FIG. 16 shows the relation between the page number of the GCP segmentand the frame address of the address segment.

FIG. 17 shows the contents of the GCP information of a page number 1 ofthe GCP segment.

FIG. 18 shows the contents of the GCP information of a page number 2 ofthe GCP segment.

FIG. 19 shows the contents of the GCP information of a page number 3 ofthe GCP segment.

FIG. 20 shows the contents of the GCP information of a page number 4 ofthe GCP segment.

FIG. 21 shows the contents of the GCP information of a page number 5 ofthe GCP segment.

FIG. 22 shows the contents of the GCP information of a page number 6 ofthe GCP segment.

FIG. 23 shows the contents of the GCP information of a page number 7 ofthe GCP segment.

FIG. 24 shows the contents of the GCP information of a page number 8 ofthe GCP segment.

FIG. 25 shows the contents of the GCP information of a page number 9 ofthe GCP segment.

FIG. 26 shows the contents of the GCP information of a page number 10 ofthe GCP segment.

FIG. 27 is a block diagram showing the constitution of an optical discdriving device according to the present invention.

FIG. 28 illustrates the focusing capturing in the optical disc drivingdevice.

FIG. 29 is a timing chart showing the sampling timing for taking out theclock information from the playback signal waveform of wobbling pits inthe optical disc driving device.

FIG. 30 is a block diagram showing the constitution of a scramblingcircuit provided in a recording/reproducing circuit in the optical discdriving device.

FIG. 31 shows a scramble table of the scrambling circuit.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to the drawings, preferred embodiments of the presentinvention will be explained in detail.

First, the format of the optical disc according to the present inventionis explained. The optical disc of the present invention is a zoneCAV-sample servo system optical disc. Meanwhile, the present inventionis explained with reference to a replay-only ROM disc and a recordableMO disc. Unless specifically defined, the following description isdirected to common contents of the two discs.

The optical disc according to the present invention has its full turn ofa track divided into 1,400 segments (segment 0 to segment 1399) as shownin FIG. 1. These segments are classified into address segments ASEG anddata segments DSEG.

In each track of the address segment ASEG, the position informationalong the radius of the disc, that is track numbers, and the position inthe tangential direction of the track, that is the segment numbers, arepre-recorded by pits. During fabrication of the optical disc, pits areformed based upon this position information. The address segments ASEGare present every 14 segments, such that there are 100 address segmentsin each track. An area from a given address segment ASEG to the nextaddress segment ASEG is one frame, such that there are 100 frames in onetrack, as shown in FIG. 8. The 13 segments between two neighboringaddress segments ASEG are segments DSEG. There are 1300 data segmentsDSEG in one track. Each segment is comprised of an area corresponding to216 servo clocks, namely 24 servo clocks and 192 servo clocksconstituting a servo area ARs and a data area ARd, respectively. Withthe address segment ASEG, the data area ARd is constituted by an addressarea ARda and a laser control area ARdb.

Referring to FIGS. 2A to 2D, the format of a MO disc is explained. Inthe servo area ARs, three pits Pa, Pb and Pc, each 2 servo clocks long,are pre-recorded with a center-to-center spacing from each othercorresponding to five servo clocks, as shown in FIGS. 2A to 2E. There isalso provided a focusing sample area ARfs having a length correspondingto six clocks in the servo area ARs.

By setting the bits Pa, Pb and Pc of the servo area ARs so as to be twoservo clocks long, the portions free of pits, namely mirror portions,are diminished, thus rendering it difficult to generate ghost bitsduring disc molding. Since RF signals can be stably reproduced from thepits Pa, Pb and Pc during accessing, various servo signals, such astracking servo signals, can be stably produced based upon RF signalsreproduced from the pits Pa, Pb and Pc. In addition, by separating thecenter-to-center distance between the pits Pa, Pb and Pc by more than apre-set distance, data interference between RF signals reproduced fromthe pits Pa, Pb and Pc may be reduced significantly. For reducing thedata interference between pits, it is desirable to separate the pits Pa,Pb and Pc by not less than five servo clocks.

The second pits Pb disposed between the 11th and 12th clocks and thethird pits Pc disposed between the 16th and 17th clocks are wobblingpits, offset from the track centers by ±¼ track along the disc radius,and give the tracking error information by the difference in amplitudevalues of RF signals reproduced by these pits Pb and Pc. Also, asexplained subsequently by referring to FIG. 29, the difference inamplitude values at both shoulder portions of RF signals reproduced fromthese pits Pb and Pc gives the phase information of servo clocks, whilethe sum of the phase information gives the clock phase information whichis independent on the tracking state.

The first pits Pa at the leading end of the servo area ARs areclassified by their positions into an address mark ADM indicating thatthe segment is an address segment ASEG, a first sector mark STM1indicating that the segment is a leading segment of the sector, a secondsector mark STM2 indicating that the next segment is a segment at theleading end of the sector and a segment mark SGM not belonging to any ofthe above sector marks.

The first pit Pa becomes the address mark ADM, first sector mark STM1and the second sector mark STM2 if it is disposed at the third to fourthclock period, as shown in FIG. 2C, at the fourth to fifth clock period,as shown in FIG. 2D and at the fifth to sixth clock period, as shown inFIG. 2E, respectively. The start position for each sector is explainedsubsequently by referring to FIG. 13. The information indicated by thefirst pit Pa may be discerned by checking the position of the maximumamplitude value of the reproduced RF signal by detecting the maximumvalue of the difference, that is by the so-called differential detectionmethod, as shown for example in FIG. 3.

Since the first pit Pa at the leading end of the servo area ARs givesthe information specifying the address mark ADM, first sector mark STM1and the second sector mark STM2, it is unnecessary to record the sectornumber or the track address on the sector basis.

In the address segment ASEG, an access code ACC composed of 16-bit trackaddresses [AM], [A2], [A3] and [AL] and the parity [P], and a frame codeFRC, composed of frame addresses [FM] and [FL], are pre-recorded as pitsin the gray code as the position information along the radius of thedisc and as the position information along the tangential direction ofthe disc, respectively, as shown in FIG. 4. The 16 bits of the trackaddress of the access code ACC are divided into groups each made up offour bits, and converted by table conversion based upon a gray codetable shown in FIG. 4 in the sequence of AM=15 to 12 bits (MSN), A2=11to 8 bits (2SM), A3=7 to 4 bits (3SM) and AL=3 to 0 bits (LSN). If andonly if the lowermost one of the four bits is [1], each of the nextfollowing four bits is its 1's complement. Thus these access codes arechanged only by one pattern between neighboring tracks. The access codesare classified by the bit positions of the access codes into groups [15,11, 7, 3], [14, 10, 6, 2], [13, 9, 5, 1] and [12, 8, 4, 0] and a paritywhich becomes 1 when the number of bits [1] in each group [15, 11, 7,3], [14, 10, 6, 2], [13, 9, 5, 1] and [12, 8, 4, 0] is even is recorded.

Thus, by using a 1′ complement for each of next 4 bits only if the lowermost bit of previous four bits is [1] so that these access codes arechanged by only one pattern between neighboring tracks, the center oneclock region bit is formed for [0] in which a pit indicating the graycode of the upper two bits and a pit indicating the gray code of thelower two pits are at the shortest distance, and for [F] in which one isat the shortest distance and the other is at the longest distance, sothat the center one-clock area does not become a continuous mirror areain the radial direction and hence the resin flow may be uniformed duringdisc molding to render it possible to mold a disc of high quality.

FIG. 5 shows a portion of the access code ACC.

As for the frame code FRC, the information in the tangential directionof the address segment ASEG, that is the 8-bit frame address specifyingthe frame number, is divided into upper four bits and lower four bits,with the upper four bits FM=7 to 4 bits (MSN) and the lower four bitsLM=3 to 0 bits (MSN), are recorded in the from of gray code in the sameway as for the access codes explained above. Although the 8-bitinformation can be recorded as the frame codes, there are only thevalues of 0 to 99 of the number of the address segments ASEG.

Meanwhile, a focus sample area ARfs of the servo area ARs is the mirrorportion and is used in the optical disc driving device for focusingservo, read power APC (automatic power control) or RF signal clamping.The positions of various sample pulses for theses operations aredifficult to identify correctly, such that variations not larger than ±5servo clock pitches may be estimated. Thus the mirror portion has anarea of 6 clocks as a space for sampling with a correct value withoutbeing affected by level modulation of RF signal level by pits despitethese variations.

On the other hand, the data area ARd of the data segment DSEG is made upof the data area ARd of 176 to 368 data clocks for recording user data,a pre-write area AR_(PR) of 12 data clocks and a post-write area AR_(PO)of four data clocks, as shown in FIG. 6. The number of data clocks ischanged with zones. The pre-write area AR_(PR) is provided as a clamparea for securing a distance necessary for pre-heating since start oflaser illumination by the driving device until the disc reaches a stabletemperature for recording in case the disc is a MG disc and forsuppressing variations in DC due to double refraction of MO signals. Forassuring format interchangeability, the ROM disc is also provided withthe pre-write area AR_(PR). The post-write area AR_(PO) is provided forassuring a distance for eliminating insufficient erasure of recordeddata and for avoiding interference of data otherwise caused by the edgeof the groove Gr provided on the MO disc. The MO disc isunidirectionally bulk-erased at the time of shipment. By recording dataof the same magnetic properties as those in the bulk erasure directionon the pre-write area ART_(PR), recorded data remains unchanged even ifdata cannot be correctly recorded on the pre-write area AR_(PR) due toinsufficient residual heat of the recording medium, so that stablesignal may be reproduced. In addition, it is effective to provide a datastring stabilized at a constant value for decoding from rear data inviterbi decoding by recording the same data of four data clocks in thepost-write area AR_(PO).

FIG. 6 shows the case of a MO disc. In the case of the ROM disc, thegroove Gr in FIG. 6 is deleted.

Since stable signals may be produced when clamping is performed duringreproduction using the pre-write area AP_(PR), an accurate clampingoperation may be performed.

It is noted that, since no pits are pre-formed in an area for datare-writing, the mirror area width is larger than with the replay-onlyoptical disc in which both data and pits are pre-recorded as pits.Therefore, by providing a groove Gr in an area corresponding to the dataarea ARd, as shown in FIG. 6, it becomes possible to diminish the mirrorportion to alleviate ill effects of disc molding on servo pits. Sincethe groove Gr is not employed for tracking control, it is not requiredto be particularly precise. In the present embodiment, the groove has adepth of λ/8, where λ is the laser wavelength. With the replay-only ROMdisc, the anchor pit Pan having a region of 3 data clocks is provided ata leading portion of the data area ARd, as shown in FIG. 7, the mirrorportion may be diminished to alleviate ill effects of disc molding onservo pits.

Each data sector is made up of 66 bytes of reference data, 2048 bytes ofuser data (D0 to D2047), 256 bytes of ECC (E1,1 to E16, 16), 8 bytes ofCRC (CRC 1 to CRC 8) and 40 bytes of user defined data (UD), totallingat 2418 bytes, as shown in FIGS. 8 and 9. The data format for 2352bytes, excluding 66 bytes of the reference data, is shown in FIG. 9.

Referring to FIG. 10, showing the waveform of playback signals of thereference data, four blocks, each consisting of 4 bytes of 8T patternsand 12 bytes of 2T patterns, and 2 bytes of all 0s as allowance forsetting the detected information, are recorded as the reference data.The 8T pattern is employed for setting the three-value level (high H,mid M and low L) for data detection in viterbi decoding and partialresponse (1, 1), while the 2T pattern is used for correcting thedc-derived pit position shift, caused by e.g., recording powervariation, during reproduction.

In the data area ARd of the data segment DSEG, data other than the 66bytes of reference data are scrambled. The scrambled data are NRZIconverted and recorded on the segment basis

In addition, this optical disc is a so-called zone CAV disc, and is madeup from the outer rim part of a gray code part area of 736 tracks,2-track buffer track, 5-track control track, 2-track buffer track,5-track control track, 848 track user zone 0, 864-track user zone 1,880-track user zone 2, 912-track user zone 3, 944-track user zone 4,976-track user zone 5, 1024-track user zone 6, 1056 track user zone 7,1120 track user zone 8, 1184 track user zone 9, 1216 track user zone 10,1296 track user zone 11, 1392 track user zone 12, 1488 track user zone13, 1696 track user zone 14, 770 track user zone 15, 5-track test track,2-track buffer track, 5-track control track, 2-track buffer track and820-track GCP area, as shown in FIGS. 11 and 12.

If, with the number of tracks Tz in a zone, the number of data segmentsDsz required for a sector in a zone, and the number of data segments pertrack of Dt, the sector is to be completed from zone to zone, and thenumber od sectors is to be constant, if suffices to decide the number oftracks so that the number of sectors Sz in a zone is

Sz=Tz*Dt/Ssz

and

Tz=K*Dsz

All parameters may be obtained by allocating the approximate datacapacity per zone, obtained on dividing the data capacity of the entiredisc by the total number of zones as the value of K, from the outer rimside zone, and determining the data clock frequency so that therecording density of the inner most track of the zone will not exceed apre-set density. The sector capacity is assumed to be constant at 2352bytes.

In this case, a sector is started at a certain segment, the sector isterminated if the number of segments making up one sector is terminatedand the next sector is started as from the next segment without startingthe next sector at a redundant byte, if any, present in the lastsegment, as shown in FIG. 13.

Thus a sector may be constituted in which a segment 0 of the frame code0 is at the leading end of a zone. If a parity sector is provided for anumber of sectors, the capacity of a parity sector may be renderedconstant by uniforming the number of sectors for each zone.

The number of sectors in the inner most zone is likely to be the not thesame as the number of the other zone by reason of the recording area.Thus the track in which the sector is terminated at the segment 1399 isto be the inner most zone.

The optical disc has the user zone divided into 16 zones as describedabove and the number of data bytes per segment (bytes/seg) and thenumber of segments per sector (seg/sector) are determined by data clocksDCK generated by multiplying the servo clock SCK by M/N where M is thevalue of the clock in FIG. 11 and N is equal to 24. That is, if thenumber of servo clocks in the servo area ARs is N and the data clocksDCK is the servo clock SCK times M/N, the number of servo clocks SCKsegand the number of data clocks DCKseg in one segment are givenrespectively by

SCKseg=9N, and

DCKseg=SCKsegM/N,

where M and N are integers.

Meanwhile, each track is divided into 1400 segments, of which 1300segments are data segments DSEG. In the GCP area, the user data is notrecorded. Therefore, 100 of the 1300 data segments DSEG are used as GCPsegment GCPseg for storing the GCP information such as mediainformation. The GCP segment GCPseg is allocated to a data segment at amid position of each address segment ASEG as shown in FIG. 14.

The GCPO segment GCPseg is made up of the servo area ARs, the GCP areaARgcp and a blank ARblk, as shown in FIG. 15. In the GCP area ARgcp,there are recorded by pits seven 4-bit data coded in the gray coderepresentation in the same way as for the access code ACC for theaddress segment ASEG, namely the GCP codes [GCPH], [GCP2], [GCP3] and[GCPL] and parity [P] and page numbers [PNH] and [PNL].

To the GCP code is appended the parity [P] in order to permit errordetection. The page numbers [PNH] and [PNL] are also appended in orderto give plural information data on media or the like as the GCPinformation. If the page numbers [PNH] and [PNL] are up to 16 pages, thesame information may be recorded as [PNH] and [PNL] for providingprotection against errors.

By arranging the respective GCP segments GCPseg in the state in whichlower one digit number of the address recorded in the address segmentASEG (frame number) is coincident with the page number of the GCPsegment GCPseg, as shown in FIG. 16, readout errors in the page numberof the GCP segment GCPseg may be eliminated. Since there are 100 framesin each track turn, 10 pages or 10 sorts of the GCP information may berepeatedly recorded ten times for reducing the opportunity of misreadingof the ten sorts of the GCP information.

As for the GCP information recorded on the GCP segment GCPseg, the pagenumber 0 is the information giving the media information/media type, asshown in FIG. 17. The bits 15 to 14 give the information concerning thephysical format of the media, such as the possible presence of thegroove or sector marks, the bits 7 to 4 give the information as to themedia form, such as Mo or ROM and bits 3 to 0 give the media generationinformation.

The GCP information of the page number 1 is the information specifyingthe data information/error correction form, as shown in FIG. 18. Thebits 15 to 8 give the data information specifying the sample servosystem, logical CAV or NRZI coding etc. and bits 7 to 0 give theinformation specifying the error correction codes.

The GCP information of the page number 2 is the information specifyingthe outer rim SFP track physical address and the bits 15 to 0 give theinformation specifying the physical address of the outer rim sidecontrol track, as shown in FIG. 19.

The GCP information of the page number 3 is the information specifyingthe inner rim SFP track physical address and the bits 15 to 0 give theinformation specifying the physical address of the inner rim sidecontrol track, as shown in FIG. 20.

The GCP information of the page number 5 is the information specifyingthe outer rim control track clock ratio/number of segments per sector asshown in FIG. 22. Bits 15 to 8 give the information specifying thenumber of clocks of the outer rim control track, that is the value ofthe clock M of FIG. 11 and bits 7 to 0 specify the informationspecifying the number of segments per sector.

The GCP information of the page number 6 is the information specifyingthe inner rim control track clock ratio/number of segments per sector asshown in FIG. 23. Bits 15 to 8 give the information specifying thenumber of clocks of the outer rim control track, that is the value ofthe clock M of FIG. 11 and bits 7 to 0 specify the informationspecifying the number of segments per sector.

The GCP information of page number 7 is the information specifying thenumber of cocks per segment/number of servo clocks per segment, as shownin FIG. 24. Bits 15 to 8 give the information specifying the number ofclocks per segment and bits 7 to 0 give the information specifying thenumber of servo clocks per segment.

The GCP information of page number 8 is the information specifying thenumber of segments per track, as shown in FIG. 25.

Bits 15 to 0 give the information specifying the number of segments pertrack.

The GCP information of page number 9 is the information specifying thenumber of address segments per track/spare, as shown in FIG. 26. Bits 15to 8 give the information specifying the number of address segments pertrack and bits 7 to 0 is the spare information.

On the control track are recorded the above-mentioned 20-byte GCPinformation, laser wavelength, reflectance or track pitch, 10 bytes ofmedia information, the number of bytes or various physical tracks ordata fields, number of data clocks of various areas, and number ofzones, and 320 bytes of the band information such as zone definitiondata.

By recording the information A specifying the number of tracks per track(1byte) (A=number of segment/track), the information B specifying thestart track number of each zone (2 bytes), the information specifyingthe total number of tracks of each zone (2 bytes) and the information Dspecifying the number of segments per sector (1 byte) (D=number ofsegments/sector) the physical track address or the physical segmentaddress may be found from the serial sector address in the followingmanner.

That is, by converting the serial sector address into zone number E andoffset number F using a table, and by executing an operation

F×D/A=G (product) . . . H (remainder)

from the offset number F, the physical track address and the physicalsegment address may be calculated within the zone by Physical trackaddress=B+G Physical Segment Address=H

As described above, with the optical disc of the embodiment illustrated,the address mark ADM or the sector marks STM1 and STM2 are recorded inthe servo area ARs, the information specifying the address segment ASEGor the leading end of the sector may be given without increasingredundancy of the data area ARd. Since each sector mark STM1, STM2specifies the leading end data segment DSEG of the sector or a segmentdirectly before the leading end data segment, the sector is notdefective even if one of the sector marks is defective, thus loweringthe rate of occurrence of defective sectors.

With the above-mentioned optical disc, by recording servo pits having alength corresponding to two clocks with respect to the generated servoclocks SCK in the servo area ARs, the mirror portion in the servo areaARs may be reduced, thereby reducing ghost pits generated during discmolding. By having a pit distance of not less than 5 shortest pit width,data interference may be suppressed for giving stable servo signals.

On the other hand, since scrambled recording data are recorded as NRZImodulated data on the optical disc, the recording pattern is randomizedand the probability of fixed patterns being continuously generated maybe lowered. Thus the disc molding may be stabilized and the memorycapacity of the reproducing apparatus in viterbi decoding may bereduced.

In addition, it is possible with the above optical disc to secureresidual heating time by the laser beam by the pre-write area AR_(PR)and post-write area AR_(PO) provided in ten data area ARd of the datasegment DSEG, so that data may be recorded positively in the data areaARd.

In the above optical disc, since the servo information and the addressinformation are given by the servo area ARs and the address segment ASEGprovided at equiangularly divided positions, the address information maybe read in the playback system by servo clocks SCK produced by the servoinformation without regard to data recording/reproduction, therebyenabling stable high speed seeking. Since plural zones with uniformnumber of sectors are equal in data capacity, there is no necessity ofchanging the numbers of the parity sectors or exchange sectors from zoneto zone, thus simplifying the control software.

On the other hand, since the last segment of a zone is continuous to thestart segment of the next zone, no wasteful segments are produced. Inaddition, since the start segment in each zone is arranged at the sameposition of each track, and each zone is started from the segment of thesame segment number, zone management may be facilitated.

In addition, since the GCP area across plural tracks give the mediainformation in the gray code with the same format as that of the addressinformation recorded in the address segment ASEG, the decoder fordetecting the address information may be used simultaneously as adecoder for exclusively reading out the media information by thereproducing apparatus. There is no necessity of a special signalgenerator during cutting. In addition, the address information may alsobe read during readout of the GCP area by the reproducing apparatus, sothat the pickup position may be managed positively.

With the optical disc, the media information specifying the sort of themedium or the format may be given by the GCP area to the reproducingapparatus.

It is also possible with the optical disc to supply the information forreading the control track information by the GCP area.

Since the media information of the same contents are given by the GCParea for one track turn, the media information of high reliability maybe given to the reproducing apparatus.

Since each segment disposed radially of each track of the GCP area ofthe optical disc gives the same media information, the media informationmay be read out without applying tracking on the reproducing apparatus.

In addition, since the GCP area provided in the vicinity of the innerand outer rims of the optical disc gives the same media information, anyof the inner rim side access start or the outer rim side access startmay be selected on the side of the reproducing apparatus.

The recording/reproducing apparatus having the MO disc and ROM dischaving such format is comprised of a control circuit block and a discdrive 200, as shown in FIG. 27. The basic arrangement of therecording/reproducing apparatus shown in FIG. 27 is the same as shown inJP Patent Application No.5-24542. With the present recording/reproducingapparatus, exchange of commands and data is executed with the hostcomputer connected via the SCSI interface.

Processing for exchange of commands and data is by a controller 101 ofthe control circuit block 100. The controller 101 appends CRC and errorcorrection codes to data from the host computer 300 during recording andtransfers the data to the disc drive 200. For reproduction, data fromthe disc drive 200 is corrected for errors and user data portions aretransferred to the host computer 300. Commands to the servo system andrespective blocks of the disc drive 200 are given by a digital signalprocessor (DSP) 102 which performs necessary processing responsive tocommands from the controller 101.

With the present recording/reproducing apparatus, the DSP 102 isresponsive to a request from the host computer 300 in the state in whichthe optical disc 201 is loaded by a loading unit 200 on a spindle motor203 to command a spindle driver 204 via an I/O block 103 to run thespindle motor 203 in rotation. The DSP may also issue a similar commandwhen the optical disc 201 is loaded when the automatic spin mode is set.When the spindle motor 203 reaches a pre-set rpm, the spindle driver 204issues a spindle on/off signal SPD to apprise the DSP 102 that therotation has been stabilized. During this time, the DSP 102 shifts anoptical pickup 205 by the pickup driver 105 via a pulse width modulating(PWM) circuit 104 until it is caused to bear against stops 200A, 200B inthe vicinity of the outer or inner rim of the optical disc 201 forpositioning a beam spot in the recording area, that is in e.g., a GCParea outside the zones 0 to 15, as shown in FIG. 28. If focusing iscaptured in the recording area, there is a risk of inadvertent dataerasure if the disc is a highly sensitive disc, such as MO disc. Bycapturing focusing in an area having data formed by pits, such as theGCP area, outside the recording area, inadvertent data erasure may beprohibited from occurrence.

It is possible with the DSP 102 to discern whether the optical disc 201is the replay-only optical disc or a recordable MO disc. Since the mediainformation is recorded in the GCP area in the gray code and with thesame format as that of the address information, the address informationand the media information may be read and discerned by the same method.In addition, since the media information in the gray code is recorded inthe GCP area of plural tracks, the media information may be reliablyread even if the beam spot position control is inaccurate.

When the spindle motor 203 reaches a constant rpm and the pickup 205 ismoved to e.g. the vicinity of the outer rim, the DSP 102 sets a biascurrent LDB for a laser diode 207 provided in the optical pickup 205 fora laser driver 206 via a D/A converter 107 from the I/O block 106 andissues a command to a servo timing generator (STG) 108 controlling theon/off of the laser diode 207 to emit a laser light. The bias currentLDB is set to a high level and to a low level during recording andreproduction, respectively. When the laser light is emitted by the laserdiode 207, the laser light enters a photodetector 208 provided in theoptical pickup 205 and a detection output by the photodetector 208enters a multiplexor 109 as a front APC signal F-APC converted into avoltage by an I-V conversion block via a current-voltage (I-V)conversion and matrix amplifier 209.

The front APC signal F-APC is digitized by an A/D converter 110 as asignal time-divisionally multiplexed by the multiplexor 109 so as toenter the DSP 102 via I/O block 111. The DSP 102 recognizes the lightvolume of the laser light by the digitized front APC signal F-APC andvaries the bias current LDB based upon the light volume control datacalculated by the enclosed digital filter for controlling the outgoinglight from the laser diode 207 to be constant.

The DSP 102 cause the current to flow from the PWM circuit 104 to thefocusing driver of the pickup driver 105 for vertically driving thefocussing actuator of the pickup 205 for focusing search state. Thelaser light reflected back from the optical disc 201 is detected by thephotodetector 208. A detection output of the photodetector 208 isconverted by an I-V conversion block of the I-V conversion and matrixamplifier 209 into a voltage which is supplied as a focussing errorsignal FE to a multiplexor 109.

Similarly to the front APC signal F-APC, the focusing error signal FE isdigitized by the A/D converter 110 as a signal time-divisionallyselected signal by the multiplexor 109 so as to enter the DSP 102 viathe I/O block 111. The DSP 103 feeds back the focusing control dataobtained on digitally filtering the focusing error signal via the PWMcircuit 104 to the focusing driver of the pickup driver 105 forconstituting a focusing control servo loop. When the focusing controlbecomes stabilized, RF signals (for ROM disc) or MO signals (for dataarea of MO disc) from the pre-write area AR_(PR) obtained by the I-Vconversion and matrix amplifier 209 from a detection output by thephotodetector 208 has its amplitude stabilized to some extent and isconverted by an A/D converter 113 into analog signals after beingclamped by a selector and clamp 112. By performing clamping using thepre-write area AR_(PR), stable signals can be produced and an accurateclamping operation may be achieved.

The A/D converter 113 is selectively fed with the servo clock signal viaa clock selector 115 from a servo clock generating (SPLL) circuit 114 ora data clock signal DCK from a data clock generating (DPLL) circuit 117.The clock selector 115 is controlled by a servo timing generator (STG)108 for selecting the servo clock signal SCK responsive to the playbackRF signals from the servo area and for selecting the data clock signalDCK responsive to the playback signal from the data area.

The clocks during servo capture operation are of a frequency in thefree-running state of the servo clock generating (SPLL) circuit 114. Forthe timing pulse during clamping, a signal obtained onfrequency-dividing the servo clock signal of the free-running frequencyby a pre-set value is employed.

The SPLL circuit 114 checks the amplitude of RF signals digitized by theA/D converter 113 to check a bit patterning order to search the samepattern as that of a pre-set pit row in the servo area. If this patternis found, the window is opened at a timing of appearance of the nextpattern, that is at a servo area of the next frame, and checks forpossible pattern coincidence. If this operation is confirmed a pre-setnumber of times, the phase of the servo clock SCK generated by the SPLLcircuit 114 is deemed to be locked with respect to the phase of rotationof the optical disc. From sampling data b1, b2 of sampling points atboth shoulders spaced one servo clock towards front and back from thecenter point of the playback RF signal waveform with respect to thewobbling pit Pb sampled at timings T_(b1), t_(b2), t_(c1) and t_(c2) ofthe servo clocks and sampling data b1, b2 of sampling points at bothshoulders spaced one servo clock towards front and back from the centerpoint of the playback RF signal waveform with respect to the wobblingpit Pc, an operation

(phase error data)=[(b2−b1)+(c2−c1)]/2

is carried out for detecting the phase error of the servo clocks SCK andservo data, as shown in FIG. 29. Thus the phase information is obtainedby taking an amplitude difference at both shoulders of the wobbling pitsPb and Pc within the servo area. The phase information derived from thetwo wobbling pits is added to the phase information for absorbing gainvariation produced form amplitude changes due to the tracking position.

If the SPLL circuit 114 is locked, it is possible for the optical discreproducing apparatus to recognize the scanning position of the pickup205 on the segment basis, so that the position of the first pit Pa canbe recognized. Fur windows A, B, C and D shown in FIG. 3 are opened andthe position which gives the maximum amplitude among the RF signalssamples at the four positions A to D is searched. If the result is theposition A, it can be recognized that the address mark is the addressmark ADM and this segment is the address segment at the leading end ofthe frame. Thus it becomes possible to clear an enclosed frame counter,not shown, for frame synchronization. Since each frame is made up of 14segments, a window is opened every 14 segments. If continuousrecognition as an address mark is possible, frame synchronization isjudged to be locked.

On frame synchronization, the address recording position can berecognized, so that the access code ACC and the frame code FRC aredecoded by an address decoder (ADEC) 116. With the ADEC 116, the patternof four bits coded in a gray code is decoded by checking the coincidencewith the gray code table shown in FIG. 4. The ADEC 116 samples theplayback RF signals at positions a, b, c and d shown in FIG. 4 and findsthe maximum amplitude position by a differential detection method.Similarly, the playback RF signals are sampled at respective positionse, f, g and h shown in FIG. 4 and the maximum amplitude position isfound in order to effect decoding by the combination and the gray codetable. By the above process, the track address [AM] to [AL], parity [P],and the frame address [FM] and [FL] are decoded and the decoded resultsare stored in a register. When the data is established, the DSP 102reads out the decoded results stored in the register for detecting thecurrent position of the pickup 205. Since it is not the four bits butthe entire pattern that is coded in gray code, comparison with aninverted table or a non-inverted table is executed depending uponwhether the LSB of the upper four bits is [1] or [0]. If, when theinitially decoded frame code FRC is loaded on a frame counter, and anumber obtained on incrementing the frame counter on the frame basis iscompared to the actually reproduced frame code FRC, continuouscoincidence is confirmed, rotation synchronization is deemed to beestablished. By returning the number obtained from the frame counter asthe fame code FRC to the DSP 102, there is no risk of the mistakenrecognition of the frame position despite some defects.

The ADEC 116 decodes the GCP information in a similar manner to thetrack address and the frame code FRC. However, it is not the addresssegment but the decoded results stored in the register at the GCPsegment GCPseg having the GCP information recorded thereon, that is readout. Thus the contents of the GCP area ARgcp may be confirmed.

On the other hand, the DSP 102 calculates the speed of movement of thepickup 205 as it reads the gray coded track address during seek forcontrolling the slide motor of the pickup driver 205 via a slide driverof the pickup driver 105 for the PWM circuit 104 for shifting the pickup205 to a target track.

When the pickup 205 reaches the target track, the tracking operation isexecuted. The tracking error signal THE is obtained by taking adifference of the amplitudes of RF signals reproduced from wobbling pitsin the servo area. The DSP 102 feeds back the tracking control dataresulting from digitally filtering the difference value to the pickupdriver 105 via the PWM circuit 104 for constituting a trackingcontrolling servo loop.

The lading position of the target sector is detected while tracking isapplied. There are the sector marks STM1 and STM2 in the leading segmentand a directly previous segment for each sector, as described above. Therespective sector marks STM1, STM2 open the windows at the fourpositions A, B, C and D shown in FIG. 3. If the maximum amplitudeposition among the RF signals sampled at these four positions A to D isB, it specifies the leading end segment of the sector, whereas, if themaximum amplitude position is C, it specifies the segment directlyprevious to the sector. Basically, the segment at the leading end of thesector is determined by converting the sector address given by the hostcomputer 300 into a physical sector and finding in which segment ofwhich track the sector is located. The probability of the two kinds ofsector marks becoming simultaneously defective is empirically not higherthan 10⁻¹⁰, such that the probability of occurrence of defective sectorsis extremely small.

The data clock generating circuit (DPLL) circuit 117 generates dataclocks DCK obtained on multiplying the frame-synchronized servo clocksSCK obtained by the SPLL circuit 114 by M/N and sends the data clocksDCK to a timing generator 19 and a recording/reproducing circuit 120.The data clocks DCK generated by the data clock generating circuit(DPLL) 117 are phase-compensated by a read clock phase compensation(RCPC) circuit 121 based upon the phase in the read phase clockcompensation area of the playback RF signals of the reference data shownin FIG. 10.

The recording/reproducing circuit 120 is fed during the recording modewith user data via the controller 101 from the host computer 300. Therecording/reproducing circuit 120 has a scrambling circuit having theconstitution shown in FIG. 30.

The scrambling circuit shown in FIG. 30 is made up of a 7-stage flipflop131, a first adder 132 for EXORing the outputs of the first and laststages of the flipflop 131 for feeding back the result to the firststage of the flipflop 131 and a second adder 133 for EXORing the outputof the first adder 132 and the recording data. By the flipflop 131 beingcleared at each sector start timing, the scrambling circuit generatesrandom numbers of 127 periods shown in a scramble table of FIG. 31 as anoutput of the first adder 132. On the other hand, by the second adder133 EXORing the recording data and the random number, the scramblingcircuit performs scrambling on the sector basis in accordance withY=X⁷+X+1.

The recording/reproducing circuit 120 modulates the scrambled user datainto NRZI data synchronized with the data clocks DCK. The initial valueof each segment is set to [0]. The modulated signal WDAT is fed via amagnetic head driver 210 to a magnetic head 211. The magnetic head 211generates a magnetic field conforming to the modulated signal WDAT andapplies the magnetic field to the data area ARd of the MO disc 201superheated to the Curie temperature by a laser beam generated by thelaser diode 207 for recording the NRZI data.

During recording, the laser drier 206 is controlled by the servo timinggenerator (STG) 108 so that the laser diode 207 will be switched fromthe playback driving power to the recording driving power at a timing ofmovement of the pickup 205 from the servo area to the pre-write area ofthe data area. The recording/reproducing circuit 120 is controlled bythe data timing generator (DTG) 119 so that data of a specified polaritywill be recorded in the pre-write area AR_(PR) at a timing the opticalpickup 205 traverses the pre-write area AR_(PR). The data of thespecified polarity means data of the same polarity as that of bulkerasure of the pre-write area AR_(PR). By recording data of the samepolarity as the bulk erasure direction on the pre-write area AR_(PR),recorded data is not changed even if data is not regularly recorded onthe pre-write area AR_(PR) due to insufficient residual heat of themedium, so that stable signals may be reproduced.

During playback mode operation, the playback MO signal obtained by theI-V conversion and matrix amplifier 209 from the detected output by thephotodetector 208 is converted into digital signals by the A/D converter113 so as to be supplied to the recording/reproducing circuit 120. Therecording/reproducing circuit 120 decodes the NRZI data by viterbidecoding after digitally filtering the playback MO signals digitized bythe A/D converter 113 in conformity to partial response (1,1). The NRZIdata is converted on the segment basis into the NRZI data which aredescrambled on the sector basis into playback data which is transmittedvia the controller 101 to the host computer 300.

The MO disc device employing partial response (1,1) and viterbi decodinghas been shown in our JP Patent Publication A-5-225638.

By scrambling recording data in this manner, the data pattern israndomized so that the probability of the continuation of a data stringhaving unified values at the time of decoding is small while the memorycapacity for viterbi decoding may be reduced. In addition, since the bitarray is randomized for the ROM disc, the bit presence/absence ratio onthe disc approaches 50% thus facilitating disc molding.

With the present recording/reproducing apparatus, the concentrically orspirally extending track is divided into plural sectors comprised ofplural segments composed of the servo area ARs and the data area ARd,and the address mark specifying the address segment ASEG having thetrack address recorded thereon, the data segment DSEG having the data ofthe leading end of the sector recorded thereon and the sector markspecifying the directly previous segment, are recorded in a servo areaof a MO disc, in which the address mark and the sector marks recorded onthe servo area ARs are detected by maximum differential value detectionby reproduced signals of the servo area by recording/reproducing meansfor recording/reproducing data on or from the target sector.

The recording/reproducing apparatus reads out the media information inthe gray code pattern with the same format as the address information ofthe address segment ASEG and reads out the control information from thecontrol track based upon the media information for performing controlbased upon the control information.

What is claimed is:
 1. An optical disc driving device for driving anoptical disc in which said optical disc has formed thereon a pluralityof substantially concentrically extending tracks, each track having aplurality of segments each having a servo area having a servo pit givinga servo information to a disc drive and a data area, and a pre-writearea unified to a polarity at the distal end of said data area,comprising recording/reproducing means for reproducing data from saidoptical disc and for recording data on said optical disc, driving powerapplying means for applying a low-level reproducing driving power or ahigh-level recording driving power to said recording/reproducing means,data supplying means for supplying recording data to saidrecording/reproducing means, and control means for controlling at atiming an optical pickup of the recording/reproducing means is movedfrom said servo area to said pre-write area of said data area, saiddriving power applying means so that the driving power is switched fromthe reproducing driving power to the recording driving power and saiddata supply means for supplying data of the same polarity as said onepolarity to said optical pickup, and controlling said data supplyingmeans for supplying desired data to said optical pickup at a timing saidpickup traverses said pre-write area during recording.
 2. The opticaldisc driving device as claimed in claim 1, further comprising clampingmeans for clamping said data reproduced by said recording/reproducingmeans at a timing of said pre-write area during reproduction.